Energy conversion devices: Which device converts chemical energy directly into electrical energy in practical electrical systems?

Introduction / Context:
Different transducers and sources convert one form of energy into another. Identifying which device accomplishes a specific conversion is foundational knowledge for electrical engineering and physics students. Here the focus is on chemical-to-electrical conversion, which powers most portable electronics.

Given Data / Assumptions:

• Common devices: solar cells, thermocouples, batteries, motors.
• Direct energy conversion is considered (no intermediate mechanical stage).
• Practical, widely used implementations.

Concept / Approach:
A chemical cell (battery) uses electrochemical reactions at electrodes separated by an electrolyte to generate an electromotive force. This EMF drives electrons through an external circuit, delivering electrical energy. By contrast, solar cells convert light to electricity (photovoltaic effect); thermocouples convert temperature differences to electricity (Seebeck effect); motors convert electrical to mechanical energy.

Step-by-Step Solution:
Identify the requested conversion: chemical → electrical.Match to device: electrochemical cell (battery) performs this conversion.Exclude others: solar (light → electrical), thermocouple (thermal → electrical), motor (electrical → mechanical).

Verification / Alternative check:
Everyday examples include alkaline, lithium-ion, and lead–acid batteries; all provide electrical power from chemical reactions.

Why Other Options Are Wrong:
(a) Solar cell uses photons, not chemical reactions. (b) Thermocouple uses a temperature gradient. (d) Motor converts in the opposite direction.

Common Pitfalls:
Confusing “fuel cell” and “battery”; both are chemical-to-electrical, and both fall under the broader category of chemical cells.

Final Answer:
Chemical cell (battery)